An outbreak of Eastern equine encephalomyelitis in Upstate New York during 1971.

The research paper discusses an outbreak of Eastern equine encephalomyelitis in upstate New York during 1971, specifically its impact on horses and humans, as well as its suspected transmission through wild avian species and mosquitoes.

Outbreak Overview

• The paper presents an investigation of an outbreak of Eastern equine encephalomyelitis (EEE) that happened in Upstate New York in August 1971. The outbreak resulted in the death of three horses and caused illness in a human infant.

Wild Avian Species Involvement

• As part of the investigation, the researchers collected sera from 93 wild birds in the outbreak area. Out of these, 15 reacted in hemagglutination-inhibition (HI) tests with the EEE virus, suggesting these birds were carriers of the virus.
• The species from which the EEE virus was isolated included the White-throated Sparrow, the Towhee, the Baltimore Oriole, and the Cedar Waxwing. The researchers propose that the Baltimore Orioles and White-throated Sparrows might have carried the virus into the area from a northern location.

Arthropod Involvement

• The researchers also isolated the EEE virus from five out of 159 pools of arthropods, which included the insect species Culiseta morsitans, Culex territans, and Culex restuans. This indicates that these species might be capable of acting as vectors for the EEE virus.

Human and Equine Testing

• Additionally, the investigators tested sera from 54 humans and 89 healthy horses for the presence of EEE using HI tests. All of these tests were negative, indicating that these individuals were not infected with EEE.

Unknown Vector to Equines and Humans

• The exact vector that transmitted EEE to the horses and the human infant remains unknown. Although investigators suspect that southward moving birds potentially brought the virus, the detailed mechanism of transmission to equines and humans is still unclear.